1. Field of the Invention
The invention concerns a photovoltaic solar module in plate form with an outer plate, an inner plate and a plastic interlayer joining them, in which are embedded the solar cells, where the solar cells are interconnected with one another electrically by means of several connecting conductors and where the connecting conductors are each connected so as to be electrically conductive to a connection device arranged in an opening in the inner plate.
Photovoltaic solar modules of the aforementioned construction are known from numerous publications and are employed to an increasing extent in practice, for example for photovoltaic curtain wall and roof elements or for charging batteries. In the case of solar modules in plate form, which can be flat or curved, the outer plate facing towards the sun usually consists of inorganic glass panes, preferably of highly light-transmitting glass with especially low iron content, which is also termed white glass. The outer plate can also consist of organic glass (plastics). For the inner plate, it is usual, for reasons of stability and durability, to provide glass panes of inorganic glass, where however other materials suitable for this purpose are employed, for example opaque, if necessary metallized, plastic films or film laminates.
For the interlayer joining the plates, the materials known for the manufacture of laminated glass panes are mainly used, in particular films of polyvinylbutyral (PVB) or ethylene/vinyl acetate (EVA) fused within the scope of a laminating process in an autoclave. Another product and manufacturing process provides for introducing a low-viscosity liquid monomer blend between the plates of the solar module and for it to be polymerized there. The interlayer serves in every case to secure the solar cells arranged between the inner plate and the outer plate and to embed them at least on one side.
Individual solar cells are usually interconnected electrically and joined mechanically to one another with the aid of narrow connecting conductors to form so-called cell strings which, during the course of module manufacture, are inserted jointly between the plates of the solar module. For electrical connection of the solar modules to other solar modules, to the power network or directly to a load, it is additionally necessary for each of the connecting conductors of the individual cell strings to be connected electrically conductively after module completion to an externally accessible connection device. A cell string will normally include two connecting conductors. For a solar module it is usual to use several cell strings which are arranged at a short distance from one another side-by-side between the plates.
For the connecting conductors, it is usual to employ tinned copper flat conductors with a maximum width of approximately 5 mm.
A solar module is known in practice where the six connecting conductors belonging to eight or ten cell strings are each led to a drilled hole in the inner plate formed by a glass pane. In these six drilled holes are secured metal connecting sleeves, where connection of the connecting sleeves to the single connecting conductors is established by soldering or welding. This module connection method is costly in manufacture on account of the large number of drilled holes.
2. Description of the Related Art
From DE 197 12 747 A1 a solar module is known where the connecting conductors of the cell strings are led as a conductor bundle through an opening provided in the inner plate to an external connection device arranged externally on it. Of course, with this module connection system one only requires a single opening (drilled hole) in the inner plate. As disadvantageous however have been found the projection of the connecting device past the inner plate and the low mechanical strength of the electrical connection (no strain relief of the connecting conductors emerging from the solar module). Also problematical in the case of this solar module is the sealing of the opening in the inner plate in relation to the interlayer which is sensitive to environmental influences. In the case of interlayers to be polymerized in situ, the liquid monomer blend can in addition escape from the opening.